1. Field of the Invention
This invention relates to an electric motor vehicle and a battery unit therefor, and more particularly to a battery unit for a straddling type electric motor vehicle such as an electric motor scooter or the like. The widthwise dimensions of the battery permit a large bank angle of the electric motor vehicle.
2. Description of Background Art
Electric motor vehicles are disclosed, for example, in Japanese Laid-Open Patent Application H3-243484 wherein a straddling type electric motor vehicle is set forth. In this prior art electric motor vehicle, a battery is mounted beneath a line drawn through the axes of the front and rear wheels, thereby to lower the center of gravity of the vehicle as a whole. The vehicle is also provided with a cooling air duct through which cooling air is sent to the electric motor.
However, in actual applications, the above-mentioned prior art electric motor vehicle needs to mount a box-shaped battery in a lower position on the vehicle. This results in an objectionably large dimension in the battery width across the center line of the vehicle body and consequently restricting the bank angle when taking a "lean-with" or similar driving posture.
Where a battery is accommodated in a battery box as in the above-mentioned prior art electric motor vehicle, it is desirable to provide means for effectively cooling the battery in actual applications since it generates heat at the time of charging or discharging.
Japanese Patent Application H2-162242, a prior application, the inventor discloses an embodiment, wherein a scooter type vehicle body includes a step floor, supporting a battery by means of a floor frame extended in the longitudinal direction along the lower side of the step floor. The battery is used as a power source for driving a power unit which is pivotally supported on a rear portion of the floor frame and which includes a combination of an electric motor and a belt type transmission.
Further, the above-described prior art electric motor vehicle needs a filter for removing dust, especially conductive dust which might be entrained on cooling air flows through the cooling air duct. This filter acts as a resistance to the flow of cooling air, barring improvements in cooling effect.